title: The nature and nurture of high IQ: an extended sensitive period for intellectual development.
abstract: IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.
authors.affiliation: Department of Psychology, The Pennsylvania State University, PA 16802-3106, USA. amb76@psu.edu
authors.forename: Angela M
authors.initials: AM
authors.lastname: Brant
authors.forename: Yuko
authors.initials: Y
authors.lastname: Munakata
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: John C
authors.initials: JC
authors.lastname: Defries
authors.forename: Claire M A
authors.initials: CM
authors.lastname: Haworth
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Keller
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.forename: Matthew
authors.initials: M
authors.lastname: McGue
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Petrill
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
authors.forename: Sally J
authors.initials: SJ
authors.lastname: Wadsworth
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Wright
authors.forename: John K
authors.initials: JK
authors.lastname: Hewitt
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D000328:Adult; D000368:Aged; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003423:Critical Period, Psychological; D004777:Environment; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D007360:Intelligence / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D035781:Siblings; D012931:Social Environment; D014427:Twins / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult
keywords: behavior genetics; cognitive ability; cognitive development; individual differences; intelligence